Pupillometry has been discovered to be an effective and useful non-invasive means of characterizing a subject's pupillary response and the condition of the human and animal autonomic nervous system. For example, in U.S. Pat. No. 5,187,506, Carter, it was disclosed therein that narcotics, opiates, depressants, stimulants, alcohol, and both legal and illegal drugs may produce deleterious and destructive effects on an individual's mental and physical performance. Pupillometry as described in the aforementioned patent is useful in detecting such drug or alcohol impairment. The teachings of U.S. Pat. No. 5,187,506, Carter, are specifically incorporated herein by reference. Another useful and effective pupillometer is described in U.S. Pat. No. 4,755,043, Carter. This patent describes a portable, hand-held, dynamic, automatic scanning pupillometer which is operated by a user to view a subject's pupil, and thereby obtain pupil images. The teachings of U.S. Pat. No. 4,755,043 are also incorporated herein by reference.
A main difference between the Carter '506 patent and the Carter '043 patent is that the pupillometer of the Carter '506 patent is a desktop device which may be totally operated by an alert subject whose pupil is to be imaged, while the Carter '043 patent teaches a pupillometer which is operated by a user and can be used to image the pupil of a subject in any posture and any state of alertness or consciousness. A distinct advantage of the pupillometer described in the Carter '506 patent is the incorporation of a self-centering apparatus therein so that the subject can easily and quickly center the image of the pupil on an optical block to form an image thereof. Unfortunately, the pupillometer of the Carter '043 patent does not incorporate aids to centering, and therefore a user of the device described therein must be particularly skilled in operating such a device. Thus a user of the device of the Carter '043 patent can obtain consistent and reliable measurements of pupil size only after practice and considerable painstaking concentration which is fatiguing for both user and subject.
Because of these aforementioned problems and deficiencies, the inventor of the subject matter herein claimed and disclosed has discovered that existing hand-held pupillometers and tabletop pupillometers fail to solve needs in the art for compact, portable devices which provide efficient and active images of a subject's pupil for various purposes under varied conditions of use. Additionally, with the advent of laptop and notebook computers over the last few years, electronic devices such as pupillometers can become even more portable. However, before the conception of the present invention, the art has failed to create circuitry and apparatus to move pupillometers in this direction. Furthermore, the inventor of the claimed pupillometer has found that pupillometry may be particularly useful in diagnosing Alzheimer's disease, and that a hand-held unit could be particularly useful in making such a diagnosis. However, the aforementioned pupillometers and hand-held pupillometers in general do not have the combination of compact size and centering aids to facilitate their use and therefore, do not fulfill a long-felt need in the art for a pupillometer to make accurate, reliable pupil images on subjects in any posture, position or state of alertness. Moreover, the inventor has found that a device used to display an image of the pupil on the optical unit may also display data characterizing pupil size and response to a light stimulus thus providing the user with immediate, easily read and understood dynamic pupil measurement data.